1. Field of the Invention
This invention relates generally to the field of vacuum microelectronic devices and, more particularly, to a method of fabrication of a field emission device with a lateral thin-film edge emitter.
2. Description of the Related Art
Recently, interest has grown in using cold cathode sources, including those based on field emission principles, to supply electrons in a variety of devices, particularly display devices. The electron guns or filaments currently used as thermionic cathodes in such display devices as cathode ray tubes, flood cathode ray tubes or vacuum fluorescent displays present a number of limitations and drawbacks. These include the generation of heat which not only wastes energy but can adversely affect the operation or lifetime of the device, non-uniformities in the emission current, the need for separate grid structures, and difficulties in placing a thermionic cathode source in the display device for assembly.
Various cold cathodes have been investigated as replacements for thermionic cathodes, but they also suffer limitations as well. Microtip emitter structures, sometimes known as Spindt cathodes, have been extensively researched, but they are costly to fabricate and the tips are subject to degradation in operation. Surface emitters, such as those using negative electron affinity materials, have been proposed, but they have been unable to achieve the emission uniformity needed for display applications.
More recently, carbon nanotubes have been researched and while they exhibit good emission performance, the processes used thus far involved forming the nanotubes through a carbon arc discharge process, precisely slicing the nanotubes, standing them on end, and attaching them with a vertical orientation to a plate. This process has proven to be cumbersome and expensive.
Avalanche cold cathodes have also been researched but these rely on silicon semiconductor manufacturing processes that add cost to the cathodes.
Accordingly, it would be desirable to provide a method of fabricating a field emission device to overcome the above mentioned problems.
A method for fabricating a thin-film edge emitter device includes the steps of providing a first conductive layer having a top surface; providing an insulating layer having a top surface disposed above the top surface of the first conductive layer; providing a second conductive layer on the insulating layer; and providing a well in the insulating layer over the first conductive layer and an edge in the second conductive layer proximate the well. Providing the well and the edge includes processing the first conductive, insulating, and second conductive layers by at least one of lift-off processing, photolithography processing, and processing with the use of a pre-formed insulating layer having at least one opening associated with a location of the well. The first conductive layer forms an anode. The second conductive layer forms at least one of a cladded cathode having an emissive edge and a control electrode.